Jackson provides a simple binding mechanism to create json from a Java POJO. It also provides annotations to control the generated json, but these are not always sufficient or appropriate.
Consider a use case where the POJO does not contain all the data required by the consumer of the json; and the POJO cannot be changed.
A wrapper POJO could be created around the original POJO, but that is clumsy and adds additional structure to the json. A simpler approach would generate a json tree from the POJO and then manipulate the tree.
For example, add the classname and some location metadata:
ObjectNode tree = mapper.valueToTree(data); tree.put("type", data.getClass().getCanonicalName()); tree.put("location", locationLookup.getLocation(data)); String result = tree.toString();